Hair conditioning shampoos and cosmetic soaps are well known in the art and have been described extensively in both the patent and non-patent journal literature. Cationic surfactants such as quaternary ammonium salts and anionic surfactants such as fatty alcohol sulfates and alkyl benzene sulfonates have been employed in hair rinses, soaps and shampoos as conditioning agents together with other water insoluble conditioning compounds such as silicones, waxes, grease and oils. Shampoos and soaps have always been produced in a variety of different forms such as solid bars, gels, creams and liquids.
Pearlescent shampoos are comprised of a number of ingredients such as stabilizing agents, pearlescent agents, conditioners, emulsifiers and hydrating agents. Pearlescent agents produce a shiny glow-like look to the compositions by the incorporation of substances which, after cooling, precipitate in the form of fine crystals resembling mother of pearl and which remain dispersed in the preparation. Known pearlizing agents include the mono- and diesters of glycol and glycerol with C.sub.16 -C.sub.22 fatty acids. However, most pearlescent agents of the prior art, if used by themselves, have to be heated above their melting points for incorporation into a final formulation. The heating step and the conditions after the heating, e.g., the mixing, storage and/or cooling stages are difficult to control and thus the pearlescence condition is ofttimes not optimized, i.e., less than ideal.
"Cold pearlescent concentrates" i.e., those that can be subsequently formulated at room temperature, are known to offer a more consistent final pearlescent product.
The room temperature blending not only saves energy, but also eliminates many inconsistencies that occur with high temperature mixing.
Cocodiethanolamide has been used to prepare these cold pearlescent concentrates since it is liquid at room temperature and thus does not require a melting step to prepare the formulations; however, studies have raised concern that the diethanolamine, often present as a by-product of the cocodiethanolamide production, may form potentially carcinogenic nitrosamines. Thus, the use of cocodiethanolamide in pearlescent personal hair care and skin products such as cosmetics, facial soaps and shampoos has been questioned from a health standpoint.
Furthermore, alkyl sulfates and ethoxylated alkyl sulfates such as sodium laureth (3EO) sulfate, which also can be used in cold pearlescent concentrates, have been found to cause skin irritation.
It would certainly be advantageous then, to have a safe pearlescent agent for use in shampoo, lipstick and personal skin care products without the presence of 1) the cocodiethanolamide as a component of the formulation if the health concerns have any basis whatsoever and 2) the irritation producing alkyl sulfates and ethoxylated alkyl sulfates.
U.S. Pat. Nos. 5,290,480 and 5,290,482 to Marschner et. al. disclose surfactant compositions comprising betaine/cocoamide complexes for use in shampoo and skin cleansing products. The complexes are combined with a cationic, nonionic, amphoteric or anionic surfactant to provide improved lather and conditioning characteristics. Cocodiethanolamide is widely used in these shampoo compositions. See U.S. Pat. No. 4,535,877 to Russell et. al. Cocoamidopropyl betaine is also a common shampoo ingredient often used as a conditioner or foam enhancer to increase the richness of the lather. See U.S. Pat. No. 4,490,355 to Desai.
U.S. Pat. No. 5,217,711 to DeOliveira et. al. disclose a hair treatment system consisting of a shampoo comprising, among other things, a pearlizing agent consisting of glycol distearate and a cocodiethanolamide. U.S. Pat. No. 5,019,376 to Vick teaches pearlescent "crystals" in a shampoo formulation formed by the reaction between a fatty acid and a fatty monoalcohol. U.S. Pat. No. 4,959,206 to Noguera et. al. teaches distearate of ethylene glycol and laurylsulfosuccinate as pearlescent agents but again, cocodiethanolamide is a necessary pearlescent stabilizer.
United States Pat. No. 4,938,953 to Pena discloses conditioning shampoos comprised of a fatty acid sulfate or a fatty alcohol ether sulfate, cocoamidopropyl betaine and cocoamidodiethanolamine. This composition also utilizes sodium lauryl sulfate as a stabilizing agent. U.S. Pat. No. 5,271,930 to Walele et. al. discloses the use of novel benzoic acid esters of polyalkoxylated block co-polymers as pearlescent agents in hair and skin care compositions.
Pearlizing agents conventionally can contain ethylene glycol monostearate, ethylene glycol distearate, guanine bismuth oxychloride, mica and mixtures thereof. U.S. Pat. No. 4,654,20 to Preston teaches a pearlescent shampoo wherein the pearlescing agent is a fatty acid ester, such as myristyl myristate or cetyl myristate, which is added to the shampoo base from a substantially anhydrous solubilizing agent such as a surfactant. A number of other prior art patents such as U.S. Pat. No. 4,608,392 to Jaquet et. al. describe the use of fatty alcohols and fatty acid quaternary ammonium compounds in the pearlescent blends. U.S. Pat. No. 5,019,376 to Vick et. al. also teaches the use of a quaternary ammonium compounds such as stearyl dimethyl benzyl ammonium chloride together with a C.sub.12 -C.sub.16 fatty acid and cetyl alcohol.
U.S. Pat. No. 5,213,792 to Grundemen discloses hair conditioning compositions containing a pearlescent agent comprised of glycerin, a monolauric acid ester, a C.sub.10 -C.sub.18 fatty alcohol, a quaternary ammonium compound, water and any one of a number of dyes, antioxidants and the like. All of these compositions also use cocodiethanolamide in one form or another for pearlescence or some other related function.
U.S. Pat. No. 4,777,038 to Scheuffgen discloses a free flowing pearlescent concentrate which allegedly remains stable without the sedimentation of the pearlescent crystals during storage. The composition is comprised of at least one mono- and diester of ethylene glycol or propylene glycol, a fatty acid mono-ethanolamine, ethylene glycol distearate, coconut oil and fatty alcohol. The sheen is provided by the appearance of fine, pearlescent crystals. U.S. Pat. Nos. 4,824,594, 4,948,528 and 5,017,305 to Hoeffkes et. al. all disclose and claim variations of a free flowing pearlescent concentrate comprising a C.sub.12 -C.sub.18 coconut oil fatty acid monoethanolamide, a C.sub.16 -C.sub.22 fatty alkyl ester, and at least one ethylene or propylene glycol ester or diester. These pearlescent agents act as emulsifiers which provide free flowing dispersions that allegedly combine high brilliance and stability with other cationic surfactant components.
U.S. Pat. No. 5,198,209 to Zhou et. al. discloses a conditioning shampoo comprising a mixture of anionic, cationic and nonionic surfactants and suggests the use of ethylene glycol stearate among others as a pearlescent agent. U.S. Pat. No. 5,252,325 to Bires et. al. teaches polyvinyl-pyrrolidone stabilized silicone shampoos together with a cationic surfactant and ethylene glycol distearate as a suggested pearlescent agent.
Whereas the aforementioned cold pearlescent compositions allegedly provide effective cleaning and luster-producing functionalities, all the formulations continue to use cocodiethanolamide or a derivative and/or sodium laureth sulfate as stabilizing agents for pearlescence or some other related function.
It is an object of the present invention to prepare a novel ultra-mild cold pearlescent concentrate for use in shampoos, skin creams, lipstick, hair colors and the like. More particularly, it is an object of the present invention to prepare a cold pearlescent composition that does not require the presence of the cocodiethanolamide with the potential health problem associated with the nitrosamines possibly formed by its diethanolamine by-product; or the skin irritants, i.e. the sodium lauryl or laureth sulfates. These ingredients are removed altogether from the compositions of the present invention which continue to provide shampoo, lipstick and other skin care products with excellent pearlescent effects and cleansing properties. These pearlescent concentrates also may be prepared without the need for the application of high temperatures often required for blending during the final formulation processes of the prior art.